Hi John - Try using these simple rules (they have worked for me anyway): #1 Is there enough solder volume available for the gold to dissolve into? #2 Is the soldering process of sufficient time ABOVE the melting point of the solder alloy (usually 183C) you are using? The answer to #1 is nearly always yes but it is #2 that gets most of us into trouble! The soldering process has to be long enough, hot enough to allow any gold rich solder joint regions to disperse. Although this is possible to deal with in production by closely regimenting your process recipes and profiles I think that it is impractical. I have previously suggested that working with your component vendors is a more practical solution to avoid problems. A good paper on this is: "Manufacturing Concerns When Soldering With Gold Plated Component Leads or Circuit Board Pads" by Mark Ferguson, IBM, IPC technical paper IPC-TP-1103. Dave Hillman Rockwell Collins [log in to unmask] ______________________________ Reply Separator _________________________________ Subject: Re: goldfinish on PC boards Author: [log in to unmask] at ccmgw1 Date: 11/5/96 10:44 AM = Address, = What you and everyone else are saying makes a lot of sense. However= , = how is amount of gold diluted into the SnPb controlled. Reflow and = solder rework dwell time (heat) is obviously a large contributor? T= he = amount of gold diluted is also dependent on what types of gold are = applied (Immersion Au tends to have a higher porosity than = Electroplated Au, in-turn more diluted gold in the SnPb). = = Is the gold being soluable a concern at the Reflow operation or at = rework or both. Could someone please comment on how the amount of = diluted gold can be controlled in PROCESS, without an SEM or other = Quality Control Device. = Regards, = John Gulley = = = = = = = ______________________________ Reply Separator __________________________= _______ Subject: goldfinish on PC boards Author: [log in to unmask] at Internet = Date: 11/4/96 8:52 PM = = = De: Coderre - JCCODERR BRMVM1 *************************************************************** = CLASSIFICATION NON-CLASSIFIE ( ) CONFIDENTIEL ( ) = Objet: goldfinish on PC boards = Gold is highly soluble in solder and should not affect the properties = of the solder joint if the concentration is below 3% (wt). This is true if the gold is completely dissolved in the solder and one does not = find a rich gold concentration at the interface. THis rich zone may occur= = if the temperature cycle is such that the dissolution is not complete. = This should be verified by SEM cross-sectioning Literature references are available upon request At higher gold concentrations (either local or bulk), embrittlement = will occur = Merci/Regards Directeur Ingenierie MLC / MLC ENG. MGR Dept 881/23 BRMT (tel. 514-534-6591, US tieline 552) = INTERNET ADDRESS [log in to unmask] *** R=AAacheminement de la note de SMTP2 --IINUS1 11/04/96 15:05 *** = =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D = Received: from simon.ipc.org by vnet.IBM.COM (IBM VM SMTP V2R3) with TCP;= Mon, 04 Nov 96 15:02:53 EST Received: from ipc.org by simon.ipc.org via SMTP (940816.SGI.8.6.9/940406= =2ESGI) id NAA28418; Mon, 4 Nov 1996 13:55:44 -0800 Resent-Date: Mon, 4 Nov 1996 13:55:44 -0800 = Received: by ipc.org (Smail3.1.28.1 #2) id m0vKUCo-0000WUC; Mon, 4 Nov 96 12:57 CST Resent-Sender: [log in to unmask] = Old-Return-Path: <[log in to unmask]> = Message-Id: <[log in to unmask]> = X-Mailer: DeskLink [Version B.02 95/10/31] = MIME-Version: 1.0 Date: 4 Nov 96 13:11 +0500 Sender: [log in to unmask] (Wolfgang Erat) = To: [log in to unmask] Subject: goldfinish on PC boards X-HPDESK-ID: 5627572 0 0 0 "NTMAIL " = X-HPDESK-PRIORITY: 3 X-HPDESK-SYSTEM: 525 From: [log in to unmask] (Wolfgang ERAT) = X-FROM: "Wolfgang ERAT"@[GBY/QC] X-HPDESK-TO: "A"@[[log in to unmask]] Content-Type: text/plain; Name=3D"/HPOFFICE/NETMAIL/C0947488.txt" Content-Disposition: inline; Filename=3D"/HPOFFICE/NETMAIL/C0947488.txt" X-HPDESK-SUBJECT: Message text Resent-Message-ID: <"aiyHd.0.fB3.snZVo"@ipc> = Resent-From: [log in to unmask] X-Mailing-List: <[log in to unmask]> archive/latest/7370 = X-Loop: [log in to unmask] Precedence: list Resent-Sender: [log in to unmask] = Would appreciate any source for info on effects on solderjoint = reliability when assembling (solderpaste / IR Reflow ) a full gold = (approx 30 microinches thick) finished board. What are the effects of = the gold alloying with the tinlead in the joint ? / Thank you. = *************************************************************************= ** = * TechNet mail list is provided as a service by IPC using SmartList v3.05= * = *************************************************************************= ** = * To unsubscribe from this list at any time, send a message to: = * = * [log in to unmask] with <subject: unsubscribe> and no text. = * = *************************************************************************= ** = *************************************************************************= ** = * TechNet mail list is provided as a service by IPC using SmartList v3.05= * = *************************************************************************= ** = * To unsubscribe from this list at any time, send a message to: = * = * [log in to unmask] with <subject: unsubscribe> and no text. = * = *************************************************************************= ** = *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * *************************************************************************** *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * ***************************************************************************